1. Field of the Invention
This invention relates to a process for producing ethyl toluene or diethylbenzene with minimal undesired by-product formation utilizing a specified crystalline aluminosilicate zeolite catalyst.
2. Description of the Prior Art
Alkylation of aromatic hydrocarbons utilizing crystalline aluminosilicate catalysts has heretofore been described. U.S. Pat. No. 2,904,679 to Mattox refers to alkylation of aromatic hydrocarbons with an olefin in the presence of a crystalline metallic aluminosilicate having uniform pore openings of about 6 to 15 Angstrom units. U.S. Pat. No. 3,251,897 to Wise describes alkylation of aromatic hydrocarbons in the presence of X- or Y-type crystalline aluminosilicate zeolites, specifically such type zeolites wherein the cation is rare earth and/or hydrogen. U.S. Pat. No. 3,751,504 to Keown et al. and U.S. Pat. No. 3,751,506 to Burress describe vapor phase alkylation of aromatic hydrocarbons with olefins, e.g. benzene with ethylene, in the presence of a ZSM-5 type zeolite catalyst.
While the above-noted prior art is considered of interest in connection with the subject matter of the present invention, the toluene ethylation process described herein in which undesired by-products, including light gases such as methane, ethane, propane, propylene and C.sub.4 olefins and C.sub.4 paraffins and unwanted aromatics such as benzene, ethylbenzene and xylenes are minimized utilizing a catalyst of a crystalline aluminosilicate zeolite having a constraint index of 1 to 12 and a silica/alumina ratio in excess of about 500 has not, insofar as is known, been heretofore described.
Ethyltoluene and diethylbenzene are valuable chemicals. They are also subject to dehydrogenation to produce vinyltoluene and divinylbenzene respectively. It is evident that the presence of substantial quantities of unwanted light gases or other aromatics in the ethyltoluene or diethylbenzene product of interest is highly undesirable. Some of the unwanted by-products, particularly those of aromatic configuration, have been difficult to separate from the desired ethyl-substituted product. It has accordingly heretofore been necessary to remove these unwanted by-products from the desired ethyltoluene or diethylbenzene product by expensive distillation techniques, especially in instances where said product is intended for subsequent dehydrogenation.
It is evident that the availability of ethyltoluene or diethylbenzene in which interfering by-products are absent or at least present in minimum amount would eliminate the necessity for expensive prior removal of such products.